TECHNO-ECONOMIC FEASIBILITY OF A RENEWABLE HYBRID SOURCE FOR A TECHNICAL INSTITUTE IN BHUBANESWAR

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1 TECHNO-ECONOMIC FEASIBILITY OF A RENEWABLE HYBRID SOURCE FOR A TECHNICAL INSTITUTE IN BHUBANESWAR Asit Mohanty Meera Viswavandya Department of Electrical Engineering, Department of Electrical Engineering, CET Bhubaneswar CET Bhubaneswar Sthitapragyan Mohanty Department of Computer Science & Engg, CET Bhubaneswar Abstract This paper presents a Techno economic analysis for a hybrid power generation systems for technical institute ie College of Engineering & Technology, Bhubaneswar located at kalinganager Bhubaneswar having Latitude N and Longitude E. Techno economic analysis is used for checking feasibility of a particular location for implementing micro grid. The technical and economic feasibility study of hybrid generating system composed of PV, Wind, Diesel and grid sources. HOMER (Hybrid Optimization model for Energy Resource) version is used for this purpose. HOMER is the Hybrid Optimization model for electrical Renewable developed by U. S. National Renewable Energy Laboratory used for modelling and simulation of system.the Simulation results are based on Energy-Economic optimization, Case studies and their comparison. Keywords HOMER, Hybrid system, Techno Economic Analysis I. INTRODUCTION HOMER, the micro power optimization model, simplifies the task of evaluating designs of both offgrid and grid-connected power systems. HOMER simulates the operation of a system by making energy balance calculations for each of the 8,760 hours in a year. For each hour, HOMER compares the electric and thermal demand to the energy that the system can supply in that hour. HOMER s Optimization Algorithm makes the system easier to evaluate possible configurations. For determining whether a configuration is feasible or not it estimates the cost of installing and operating the system over the lifetime of the project. The system cost is the costs of capital, replacement, operation and maintenance, fuel, and interest. HOMER allows different combination of possible resources based on economic feasibility. This paper gives the design idea of optimized Hybrid Energy System for technical institute C.E.T Bhubaneswar.1) Studying the load demand for every day in a year; 2) Introducing the solar data in HOMER software 3) Designing hybrid model. The software used for this purpose is HOMER (Hybrid Optimization Model for Energy Resources).HOMER, 32

2 the micro power optimization model, simplifies the task of evaluating designs of both off-grid and gridconnected power systems. HOMER simulates the operation of a system by making energy balance calculations of each configuration. It also determines whether a configuration is feasible or not i.e., whether it can meet the electric demand under the conditions of specification, and estimates the cost of installing and operating the system over the lifetime of the project. The purpose of this study is to find the best possible combination so that it can meet the daily electricity demand for the institute C.E.T Bhubaneswar. Hybrid energy systems combine two or more energy conversion devices. A hybrid energy system [4] is a combination of two or more energy sources to provide electric power where the electricity [5] is either fed directly to [6] grid or to batteries for energy storage. The main reason of integrating renewable energy sources in a hybrid system is mainly to save fossil fuel (diesel). So a diesel generator is generally used as a backup. In this case Hybrid system can be configured in two different configurations.. II METHODELOGY For detailed analysis,the load of C.E.T. Bhubaneswar is taken for experiment. The monthly load profile is shown in figure1 Fig.1.Monthly load profile of C.E.T. Bhubaneswar Solar radiation data for the Institute C.E.T, Kalinganagar, Ghatikia Bhubaneswar region was obtained from the NASA Surface Meteorology and Solar Energy web site [3]. The annual average solar radiation for this region is 4.72 kwh/m2/d. Fig.2. Shows the solar radiation and Clearness index over a year. Fig.2.Monthly Average Solar Radiation Fig.3 Monthly average temperature. III.PROPOSED ALGORITHM: Two different cases of hybrid system are taken (i) Wind Diesel Hybrid System and (ii) PV-Wind-Diesel Hybrid System. This section explains the detailed procedures to build the schematic and the technoeconomic analysis. CASE: 1 Wind-diesel hybrid power system Wind-Diesel hybrid power system consists of the following components. Optimization and sensitivity analysis are the two algorithms used for evaluation of the different possibility of system configuration. Two modes of operations are. III.A.Isolated mode The micro grid contains the following configuration i.e. one wind generator and two diesel generator along with battery and converter. 33

3 Fig.7.Fuel curve and Efficiency curve of 75 kw diesel engines Table 1.Cost Details Fig.4.Power curve of wind turbine Table 2.Optimization result in isolated mode Fig.5. Monthly average wind speed Fig.6. Schematic diagram of Power system in isolated mode III.B.Diesel Engines: Here 75 kw and 150 kw diesel engines are used.the Fuel curve and efficiency curve of diesel generators 75 kw and 150 kw are shown in fig.7. III.C.Economic Analysis Economic Analysis is used as it is a powerful tool used for checking the feasibility of a particular site. Here a site of institute C. E. T Bhubaneswar is selected for feasibility study of a micro grid with different configurations. This work is a technical and economic feasibility study of a hybrid power generating system, composed of PV, wind, diesel and grid resources with high reliability requirements of electric supply. Two cases (i) Wind-Diesel and (ii) PV-Wind-Diesel system have been analyzed and simulated in isolated and grid connected modes and the results have been explained in details. Homer (Hybrid Optimization model for energy Resource Version 3.6.1) used for this purpose. HOMER s optimization algorithm makes the system easier to evaluate by taking possible configurations. At each step it can calculate the cost of installing and operating the system over the completion of project. For executing the project two operations are needed i.e. i) Optimization: After simulation HOMER displays a list of possible configurations. HOMER pro is optimizing for lowest net present cost. ii) Sensitive Analysis: 34

4 HOMER repeats the optimization process by using input sensitive variable. III.D.Resources used for Techno-economic Analysis For techno economic analysis the micro grid has been designed by using the following resources such as convertor, battery and grid. The wind and solar resources data of the proposed site C.E.T, Kalinganagar Bhubaneswar is obtained from NASA's Surface meteorology. Website by giving the latitude and longitude for the selected site i.e N, E. III.E.Battery and Converter Details: Nominal Voltage (V):12.0, Maximum Capacity (Ah) : 83.4,Maximum Charge Rate (A/Ah): 1.00,Maximum charge Current (A):16.7,Maximum Discharge Current (A):24.3, Capacity Ratio c:0.403,rate Constant, k:0.827,converter : Lifetime:15 years, efficiency III.F.Grid Connected mode: Fig.9. shows the schematic diagram of grid connected Wind-Diesel Hybrid Power System. The components used in this configuration are one wind generator, grid, two diesel generators along with battery and convertor. Table 3. Optimization result with grid IV.TECHNO ECONOMIC ANALYSIS (CASE 1): Techno economic analysis of case 1 has been done by using input sensitive variable. Sensitive variable is taken as the input having multiple values. For each sensitive variable Homer performs a separate optimization. In this case diesel fuel price and wind speed are considered as the sensitive variable. Fig.8. Cost curve Fig.10.Cost summary in isolated mode Fig.9. Schematic diagram of Power system with grid Fig.11. Cost type detail in isolated mode 35

5 Table 4. Cost summary details in isolated mode Table 5. Comparison of best case with current system Fig.15.Cost summary in isolated mode using grid Table 6.Cost summary of different components using grid Fig.12. Difference between current system and Base case Table 7.Cost Summary Fig.13. Comparison of current system with Base case Fig.16. PV-WIND DIESEL Hybrid System Fig.14.Annual comparison Fig.17. Monthly average solar radiation 36

6 Table 8. Optimization result of PV-Wind-Diesel with Grid System (Grid connected Mode) Fig.18. Wind speed data Fig.19. (a) Daily and (ii) Seasonal Load Details for PV-Wind-Diesel hybrid System HOMER can perform a sensitivity analysis by accepting multiple values for a particular input variable. This analysis determines how changes in the input variable affect the performance of the system and the relative ranking of different systems. A sensitivity variable is taken as an input variable where multiple values have been specified. In this case Wind speed, diesel fuel price and global solar radiation are considered to be the sensitivity variables. A sensitivity variable analysis can result in a huge amount of output data. By performing the sensitivity analysis over a large range of wind speed, diesel price and global solar radiation described below in Table 9 Table 9. Addition of Sensitive variable Fig.20. Cost curve Three sensitivity cases (i) solar annual averages: 4.85 and 5.2 kwh/m2 /d, (ii) Wind Speed: 4.5,5,6 and 7 and (iii) Diesel fuel prices: 0.8, 0.85, 0.9 and 0.95 $/L, are considered for simulation. Table 10. Optimization result after adding sensitive variable Fig.21. PV-wind-diesel-with grid system (Grid connected Mode) 37

7 Isolated PV-Wind-Diesel System Table 11.Cost summary Fig.25. Monthly Average Electrical Production Grid Connected PV-Wind Diesel Hybrid System Cost Summary: (i)by Component Fig.26. Cost Summary By component Fig.22. Cost Summary by component Fig.27. Cost Summary By Cost Type(ii)By Cost type Fig.23. Cost Summary by Cost type Fig. 24.Cash flow Summary Fig.28. Cash flow summary 38

8 Fig. 29.Electric Production Table 12. Cost Analysis CONCLUSION This paper is mainly divided in two parts: (i) Case: 1 Wind-Diesel Hybrid System and (ii) Case : 2 Wind- Diesel-PV Hybrid System. The configurations are designed and simulated by using sensitivity input variable for getting optimal result. Both the systems are analyzed for different technical, economical and environmental point of view. The results of HOMER modeling shows that if, cost summary, cash flow summary, electrical production or emissions and cost of wind turbine, battery and converter us considered as a whole, Wind-diesel hybrid system is far better than a system with only two diesel generators. Total Net Present Cost is very low compared to cases where Diesel Only and Diesel Battery systems are employed. To summarize, addition of a wind turbine, converter and battery in existing diesel generators system is feasible. The optimal system type shows that for low diesel prices and low wind speeds, the system with two diesel generators is feasible, but as the diesel prices increases with lower wind speeds, diesel-battery system shows optimum performance. Wind-dieselbattery system approach is the best when the diesel prices and wind speeds are high. To summarize, addition of a wind turbine with two diesel generators shows better system approach in terms of Net Present Cost (NPC) and performance compared to a system with only two diesel generators. Case : 2 PV-Wind- Diesel Hybrid System : The results of the proposed scheme for isolated and grid connected modes shows that the cost summary, cash flow summary, electrical production or emissions and cost of PV-Wind-diesel hybrid system is feasible. Total Net Present Cost is $3159. From the optimal system type it is clear that at lower wind speeds, PV/Battery/Diesel configuration is optimum, at medium wind 131 speeds Wind/PV/Battery configuration is feasible and at higher wind speeds, PV/Wind/Diesel/Battery configuration shows optimum results. As wind speed increases, the penetration of PV and diesel reduces. The grid connected mode shows reduction in NPC compared to isolated mode. The proposed scheme is analyzed for variations in different parameters such as change in wind speed, change in solar radiation, change in loading conditions, increase in diesel fuel price and decrease in cost of renewable energy technologies. V.REFERENCES [1] Givler T, Lilienthal P. Using HOMER software, NREL S micro power optimization model, to explore the role of gen-sets in small solar power systems case study: Sri Lanka. Technical Report NREL/TP Availablefrom: 05. [2] Hafez O, Bhattacharya K. Optimal planning and design of a renewable energy based supply system for micro grids. Renewable Energy 2012; 45:7-15. [3] Lau KY, Yousof MFM, Arshad SNM, Anwari M, Yatim AHM. Performance analysis of hybrid 39

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